/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.format.datetime.joda;

import java.util.TimeZone;

import org.joda.time.DateTimeZone;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;
import org.joda.time.format.ISODateTimeFormat;

import org.springframework.format.annotation.DateTimeFormat.ISO;
import org.springframework.lang.Nullable;
import org.springframework.util.StringUtils;

/**
 * Factory that creates a Joda-Time {@link DateTimeFormatter}.
 *
 * <p>Formatters will be created using the defined {@link #setPattern pattern},
 * {@link #setIso ISO}, and {@link #setStyle style} methods (considered in that order).
 *
 * @author Phillip Webb
 * @author Sam Brannen
 * @see #createDateTimeFormatter()
 * @see #createDateTimeFormatter(DateTimeFormatter)
 * @see #setPattern
 * @see #setStyle
 * @see #setIso
 * @see DateTimeFormatterFactoryBean
 * @since 3.2
 */
public class DateTimeFormatterFactory {

    @Nullable
    private String pattern;

    @Nullable
    private ISO iso;

    @Nullable
    private String style;

    @Nullable
    private TimeZone timeZone;


    /**
     * Create a new {@code DateTimeFormatterFactory} instance.
     */
    public DateTimeFormatterFactory() {
    }

    /**
     * Create a new {@code DateTimeFormatterFactory} instance.
     *
     * @param pattern the pattern to use to format date values
     */
    public DateTimeFormatterFactory(String pattern) {
        this.pattern = pattern;
    }


    /**
     * Set the pattern to use to format date values.
     *
     * @param pattern the format pattern
     */
    public void setPattern(String pattern) {
        this.pattern = pattern;
    }

    /**
     * Set the ISO format used to format date values.
     *
     * @param iso the ISO format
     */
    public void setIso(ISO iso) {
        this.iso = iso;
    }

    /**
     * Set the two characters to use to format date values, in Joda-Time style.
     * <p>The first character is used for the date style; the second is for
     * the time style. Supported characters are:
     * <ul>
     * <li>'S' = Small</li>
     * <li>'M' = Medium</li>
     * <li>'L' = Long</li>
     * <li>'F' = Full</li>
     * <li>'-' = Omitted</li>
     * </ul>
     *
     * @param style two characters from the set {"S", "M", "L", "F", "-"}
     */
    public void setStyle(String style) {
        this.style = style;
    }

    /**
     * Set the {@code TimeZone} to normalize the date values into, if any.
     *
     * @param timeZone the time zone
     */
    public void setTimeZone(TimeZone timeZone) {
        this.timeZone = timeZone;
    }


    /**
     * Create a new {@code DateTimeFormatter} using this factory.
     * <p>If no specific pattern or style has been defined,
     * {@link DateTimeFormat#mediumDateTime() medium date time format} will be used.
     *
     * @return a new date time formatter
     * @see #createDateTimeFormatter(DateTimeFormatter)
     */
    public DateTimeFormatter createDateTimeFormatter() {
        return createDateTimeFormatter(DateTimeFormat.mediumDateTime());
    }

    /**
     * Create a new {@code DateTimeFormatter} using this factory.
     * <p>If no specific pattern or style has been defined,
     * the supplied {@code fallbackFormatter} will be used.
     *
     * @param fallbackFormatter the fall-back formatter to use
     * when no specific factory properties have been set
     * @return a new date time formatter
     */
    public DateTimeFormatter createDateTimeFormatter(DateTimeFormatter fallbackFormatter) {
        DateTimeFormatter dateTimeFormatter = null;
        if (StringUtils.hasLength(this.pattern)) {
            dateTimeFormatter = DateTimeFormat.forPattern(this.pattern);
        } else if (this.iso != null && this.iso != ISO.NONE) {
            switch (this.iso) {
                case DATE:
                    dateTimeFormatter = ISODateTimeFormat.date();
                    break;
                case TIME:
                    dateTimeFormatter = ISODateTimeFormat.time();
                    break;
                case DATE_TIME:
                    dateTimeFormatter = ISODateTimeFormat.dateTime();
                    break;
                default:
                    throw new IllegalStateException("Unsupported ISO format: " + this.iso);
            }
        } else if (StringUtils.hasLength(this.style)) {
            dateTimeFormatter = DateTimeFormat.forStyle(this.style);
        }

        if (dateTimeFormatter != null && this.timeZone != null) {
            dateTimeFormatter = dateTimeFormatter.withZone(DateTimeZone.forTimeZone(this.timeZone));
        }
        return (dateTimeFormatter != null ? dateTimeFormatter : fallbackFormatter);
    }

}
